There are no outcome measures for the primary objective. For the secondary objectives, the outcome measures are (1) tobacco abstinence, as determined by self-reported tobacco use, urinary cotinine, and (in tobacco smokers only) breath CO, and (2) reduction in tobacco use of at least 50% (e.g., from 10 cigarettes per day to 5 cigarettes per day). Other outcome measures for the secondary objectives include duration of abstinence, nicotine withdrawal signs and symptoms, and tobacco craving. Behavioral, psychological, medical, and genetic characteristics and tobacco-use history will be assessed at the beginning of the study as predictors of treatment outcome and at follow-up.